The proposed revised pilot study uses the R21 mechanism to measure racial and ethnic identification among mixed-ancestry adolescents in preparation for a multifaceted prospective examination of mixed-racial/ethnic identity development. The specific aims address a priority announced in PA-03-057, The Social and Demographic Studies of Race and Ethnicity, for a need to develop and validate methods of conceptualizing, measuring, and modeling race and ethnicity. Specific Aim 1. Conceptualization: We posit that mixed- ancestry identification as an act of checking one or more boxes on an assessment form imperfectly reflects an individual's underlying racial/ethnic identity. We conceptualize racial/ethnic identification as an observed indicator of an unobserved (i.e., latent) identity construct, which represents a novel approach to the study of race and ethnicity, one that captures the variability and complexity of contemporary theories of racial/ethnic identity and its manifestation in a multi-cultural society. Specific Aim 2. Measurement: We will develop a conceptually grounded measurement model of the latent tendency toward claiming a mixed-ancestry identity, informed by multiple indicators, including versions of commonly used measures (e.g., Census 2000 racial/ethnic item sets, etc), as well as phenotypic and cultural diversity. Specific Aim 3. Modeling: We will develop and demonstrate a modeling approach that assumes both single- and mixed-ancestry claims are measured imperfectly and that assignment to various racial/ethnic groupings will be based on an empirical model of this uncertainty. This unique modeling approach more closely approximates the developmental and contextual variability in all racial/ethnic self-identifications, preserves the integrity of the subpopulations in the sample, and can be used to examine both similarities and differences across individuals from various racial/ethnic backgrounds. A highly qualified research team will be assisted by an Advisory Board made up of some of the most prominent scholars in the fields of racial and ethnic studies and mixed ancestry. The significance of this study lies in the new conceptual approach to measuring mixed-ancestry identification among adolescents and also in our use of new statistical tools. The tools developed will be used to assess both the strengths and vulnerabilities of mixed-ancestry youth. [unreadable] [unreadable]